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Emulsion electrospinning is a method of modifying a fibers’ surface and functional properties by encapsulation of the bioactive molecules. In our studies, bovine serum albumin (BSA) played the role of the modifier, and to protect the protein during the electrospinning process, the W/O (water-in-oil) emulsions were prepared, consisting of polymer and micelles formed from BSA and anionic (sodium dodecyl sulfate–S) or nonionic (Tween 80–T) surfactant. It was found that the micelle size distribution was strongly dependent on the nature and the amount of the surfactant, indicating that a higher concentration of the surfactant results in a higher tendency to form smaller micelles (4–9 µm for S and 8–13 µm for T). The appearance of anionic surfactant micelles reduced the diameter of the fiber (100–700 nm) and the wettability of the nonwoven surface (up to 77°) compared to un-modified PCL polymer fibers (100–900 nm and 130°). The use of a non-ionic surfactant resulted in better loading efficiency of micelles with albumin (about 90%), lower wettability of the nonwoven fabric (about 25°) and the formation of larger fibers (100–1100 nm). X-ray photoelectron spectroscopy (XPS) was used to detect the presence of the protein, and UV-Vis spectrophotometry was used to determine the loading efficiency and the nature of the release. The results showed that the location of the micelles influenced the release profiles of the protein, and the materials modified with micelles with the nonionic surfactant showed no burst release. The release kinetics was characteristic of the zero-order release model compared to anionic surfactants. The selected surfactant concentrations did not adversely affect the biological properties of fibrous substrates, such as high viability and low cytotoxicity of RAW macrophages 264.7.

The aim of the work was to examine the possibility of using modified halloysite nanotubes as a gentamicin carrier and to determine the usefulness of the modification in terms of the effect on the amount of the drug attached, its release time, but also on the biocidal properties of the carriers. In order to fully examine the halloysite in terms of the possibility of gentamicin incorporating, a number of modifications of the native halloysite were carried out prior to gentamicin intercalation with the use of sodium alkali, sulfuric and phosphoric acids, curcumin and the process of delamination of nanotubes (expanded halloysite) with ammonium persulfate in sulfuric acid. Gentamicin was added to unmodified and modified halloysite in an amount corresponding to the cation exchange capacity of pure halloysite from the Polish Dunino deposit, which was the reference sample for all modified carriers. The obtained materials were tested to determine the effect of surface modification and their interaction with the introduced antibiotic on the biological activity of the carrier, kinetics of drug release, as well as on the antibacterial activity against Escherichia coli Gram-negative bacteria (reference strain). For all materials, structural changes were examined using infrared spectroscopy (FTIR) and X-ray diffraction (XRD); thermal differential scanning calorimetry with thermogravimetric analysis (DSC/TG) was performed as well. The samples were also observed for morphological changes after modification and drug activation by transmission electron microscopy (TEM). The conducted tests clearly show that all samples of halloysite intercalated with gentamicin showed high antibacterial activity, with the highest antibacterial activity for the sample modified with sodium hydroxide and intercalated with the drug. It was found that the type of halloysite surface modification has a significant effect on the amount of gentamicin intercalated and then released into the surrounding environment but does not significantly affect its ability to further influence drug release over time. The highest amount of drug released among all intercalated samples was recorded for halloysite modified with ammonium persulfate (real loading efficiency above 11%), for which high antibacterial activity was found after surface modification, before drug intercalation. It is also worth noting that intrinsic antibacterial activity was found for non-drug-intercalated materials after surface functionalization with phosphoric acid (V) and ammonium persulfate in the presence of sulfuric acid (V).

The development of new chemically resistant anodes for protonic ceramic fuel cells (PCFCs) is urgently required to avoid the costly deep hydrogen purification method. Ba

The halloysite/3-Aminopropyltrietthoxysilane/gentamicin hybrid was obtained as a novel carrier for sustained drug release in antimicrobial treatment. The nanocarrier was prepared by functionalizing the halloysite surface with the 3-Aminopropyltrietthoxysilane, which was introduced into the system as a coupling agent to efficiently bond the drug in to the halloysite lumen. The interaction between gentamicin, silane and halloysite as well as the antimicrobial susceptibility against E. coli, S. aureus and S. epidermidis were investigated. The results indicate that silane grafting combined with intercalation of gentamicin resulted in efficient drug bonding to the inner surface of halloysite and ultimately extended drug release from the tested hybrid.

The effect of the SrO addition on the microstructure and structure of the glazes from the SiO2–Al2O3–CaO–MgO–K2O system was investigated in this study. The results were obtained by testing the ability of the frits crystallization, the stability of the crystallizing phases during the single-step fast-firing cycle depending on their chemical composition and the effect of addition of strontium oxide. Differential scanning calorimetry (DSC) curves showed that all glazes crystallized, and diopside and anorthite were mainly identified as dominant phases in the obtained glazes, while the size and amount of each depended on the amount of SrO introduced. The thermal characteristic of the frits was carried out using DSC, and crystalline phases were determined by X-ray diffractometry. The glaze microstructure was investigated by scanning electron microscopy and transmission electron microscopy. Additional information on the microstructure of frits was derived from spectroscopic studies in the mid-infrared range.

The majority of parts used in the electrical apparatus are made of polymer materials; however, pure polymers do not provide the antibacterial functionality. Therefore, in order to add such property to them it is necessary to use antibacterial additives. The study concerned intercalation of triclosan (TCS) as biocide into montmorillonite (MMT) interlayer spaces was performed in order to increase TCS resistance to high-temperature treatment, which is necessary during polymer composite processing. The obtained MMT + TCS hybrids were tested for structural and antibacterial properties. The degree of biocide intercalation was assessed using X-ray diffractometry, by analyzing changes in MMT interlayer distance, and thermal analysis was performed to assess the effect of the intercalation process on the thermal stability of TCS. Antibacterial tests against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) were also carried out on the obtained MMT + TCS powders in order to confirm the bactericidal properties of TCS released from the clay after the intercalation process. As a final proof of concept, the hybrid powder, namely MMT with incorporated TCS, was incorporated into polycarbonate matrix and antibacterial activity of modified polymer samples was tested. The obtained results have proven that montmorillonite–triclosan hybrid is an effective antibacterial additive with enhanced thermal stability which can be applied for protection of plastic parts used in electrical devices.

The paper describes the results of research on obtaining porous membranes produced from polylactide fibers (PLA) by electrospinning, additionally modified with gentamicin antibiotic (GM) at the sta...

The paper focuses on the results of research on the development of newly designed white glazes without the addition of traditional opacifiers such as ZrO2 or ZrSiO4, intended for use in ceramic sanitary products. The effect of opacity was obtained by introducing ZnO in quantities of 4–8 wt% to the sets of glazes. ZnO introduced to the glaze compositions resulted in crystallization of gahnite, and gahnite caused the glaze to become opaque and white. Measurements of the whiteness of glazes confirmed its high level, over 90 units were noticed according to the CIE Lab scale. The microstructure and structure of the glazes were measured by scanning electron microscopy and X-ray diffractometry. The colour and gloss of the glazes were measured using a spectrophotometer and a gloss meter. The topography of the glaze surfaces, as well as the roughness level (Ra), were measured using a confocal microscope.

The paper presents the results of research on the influence of the granulometric composition on the rheological properties of granulates from soft waste produced in the manufacturing of ceramic tiles using the Lamgea and Continua methods in terms of the possibility of their reuse. The composition of the granulates was modified by removing individual grain fractions in three measurement series. Comparatively, the measurement samples for the production granulates were prepared in the same way. Microscopic observations and granulometric analysis showed significant differences in the grain shape and grain size distribution of granulates. The soft waste granulates also showed much worse flow ability than the production granulates. It was shown that the removal of the smallest fractions significantly improved the rheological properties of soft waste granulates. This tendency was also observed in the case of measurements of changes in the bulk density. A Brookfield powder analyzer was used for rheological tests, and a flow analysis was performed using the numerical Jenike classification.

In this study, we propose a new approach in the anterior cruciate ligament (ACL) replacement to provide stability and integration with bone tunnel. A polylactide (PLA)-based tubular implant was used to support the graft stabilization in femoral and tibial bones and to stimulate the healing process after (ACL) replacement on a sheep model. The ACL was replaced with an autologous Achilles tendon split graft. The tendon-to-bone healing in the model was analyzed after 6 and 12 weeks. Two groups of animals were compared, i.e. the group with the PLA-based implant used in the ACL replacement and the control group without the implant. The knee joints were mechanically and clinically evaluated, including the histopathology tests, to determine their stability and integrity. The results indicated that the bioresorbable PLA-based tubular implant may facilitate integration of the tendon graft with bone. Remodeling the allograft inside the implant improves the joint mobility from the first week of healing: no pathological changes were observed at the surgery site and in the animals’ mobility. After 6 and 12 weeks of healing no significant changes in the mechanical parameters of the knee joint were observed, regarding the joint failure force, knee displacement, angular mobility range and joint stiffness. Relatively small values of the non-destructive tests in the knee displacement, already 6 weeks after surgery, indicated the early stabilization of the knee joint. The studies showed that the failure forces of knee joints after the ACL replacement with the PLA-based implant are lower than those of an intact joint, although their biomechanical features, including strain-at- failure, are similar. The biomechanical parameters of the knee joint were significantly improved due to the selected method of attaching the autograft ends to the femoral and tibial bone surfaces. After 12 weeks the intra-tunnel tendon-bone site with the PLA implant revealed the better tibia-femur joint mechanical stability, linear force-strain function and the decreasing strain-to-failure value, as compared to the control group.

Purpose: The aim of this study was to investigate the possibility of intercalation of gentamicin and neomycin in montmorillonite (MMT) nanofillers, as well as to study the in vitro antimicrobial properties of nanocomposite films containing a small amount of thus obtained nanofillers. Methods: The polylactide matrix (PLA) nanocomposite films with drug-intercalated montmorillonite fillers were obtained by casting after intercalation of drugs in aqueous solutions. The efficiency of intercalation has been confirmed by X-ray diffraction (XRD) and Zeta potential measurements. The materials were studied for surface wettability, roughness and mechanical properties during 6 weeks of incubation in phosphate buffer saline, and their bactericidal activity was tested against Escherichia coli bacteria before and after 6 weeks of incubation in distilled water at 37 °C. The presence of antibiotics during the incubation was monitored by conductivity and pH measurements. Results: The results indicate that nanocomposite polylactide films with montmorillonite filler intercalated with gentamicin and neomycin tend to degrade faster that their counterparts with non-intercalated fillers, which affects their mechanical properties. However, drug intercalation provided an antibacterial activity, which was confirmed by the presence of zones inhibiting the growth of Gram-negative bacteria for both antibiotics. It was also confirmed that the interaction of antibiotics with clay and polimer matrix did not adversely affect this bactericidal effect. Conclusions: Montmorillonite can be successfully intercalated with both gentamicin and neomycin, and then used as active filler for polylactide films having very good antibacterial properties, therefore their use in biomedical applications can be significantly expanded.

Skin substitutes are heterogeneous group of scaffolds (natural or synthetic) and cells. We hypothesize that nanofibers with layer composition made of polylactide (PLA) and sodium hyaluronate (HA) obtained using electrospinning method are a good matrix for cell adhesion and proliferation.Optimal conditions of electrospinning of PLA and HA nanofibers to create layered compositions (PLA membrane covered with HA nonwovens) were determined by modifying parameters such as the appropriate amount of solvents, polymer concentration, mixing temperature and electrospinning process conditions. By changing the parameters, it was possible to control the diameter and properties of both polymer fibers. The spinning solution were characterized by surface tension and rheology. A scanning electron microscope (SEM) was used to determine the morphology and fiber diameters: PLA and HA. Structure of the PLA/HA nonwoven was analyzed using spectroscopy (FTIR/ATR). Biocompatibility of the nonwoven with fibroblasts (ECM producers) was assessed in the in vitro conditions.The results showed that stable conditions for the formation of submicron PLA fibers were obtained using a 13% wt. solution of the polymer, dissolved in a 3:1 mixture of DCM:DMF at 45 °C. The hyaluronic fibers were prepared from a 12% wt. solution of the polymer dissolved in a 2:1 mixture of ammonia water and ethyl alcohol. All materials were biocompatible but to a different degree.The proposed laminate scaffold was characterized by a hydrophobic-hydrophilic domain surface with a maintained fiber size of both layers. The material positively underwent biocompatibility testing in contact with fibroblasts.

The aim of this study was to develop new compositions of white glazes without the addition of ZrSiO 4 designed for sanitary products obtained in a 12-h firing cycles at a maximum temperature of 1230 °C. Alternative glazes with a good opacity and a high degree of whiteness were obtained, composed primarily of raw materials available on the domestic market in Poland. The opaque effect was achieved due to crystallisation of anorthite, which was identified as a major crystalline phase in the system. The glazes were characterised by a high whiteness value L*, greater than 90 in the CIELAB colour space, and a gloss, measured with a 60° light incident angle on the glaze surface, above 50%. The microstructure and structure of the glazes were measured with the use of a Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). The colour and gloss of glazes were measured with the use of a spectrophotometer and a gloss metre at a 60° angle of incidence. The topography of glazes surfaces, as well as the roughness level (Ra), were measured with the use of a confocal microscope.

This paper presents the characteristics of magnesium aluminium silicate–gentamicin complexes for drug delivery systems. The work describes the results of studies on the successful introduction of gentamicin (an aminoglycoside antibiotic) into the interlayers of smectite clay and examines the possible use of intercalated smectite as a carrier for sustained drug release. Characterisation of magnesium aluminium silicate–gentamicin complexes was carried out by means of X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis and scanning electron microscopy with EDX analysis. The possibility of using the gentamicin intercalated smectite as a carrier for sustained release of the drug was investigated during in vitro study, in which the release rate of gentamicin from the smectite clay matrix was monitored based on absorption at 330 nm using a UV–Vis spectrometer and the kinetic of drug release was evaluated based on the zero-order, first-order, Higuchi and Korsmeyer–Peppas models. The results confirmed the efficiency of intercalation and indicate the potential for introducing gentamicin into the interlayer space of montmorillonite. Accordingly, the obtained material may thus be used as a drug carrier in modulated drug delivery systems.

The aim of this study was to investigate the influence of the addition of smectite clay fillers to a polylactide matrix on the physical properties of the nanocomposites thus created, studied during the degradation process. A small amount of nanofiller (3–10 mass %) was used, and the clay was additionally modified with organic ammonium salt for better compatibility with the polymer matrix. Crystallisation, glass transition and melting temperature of the nanocomposites were investigated, and the resulting thermal, structural and mechanical properties were compared to those of a neat polylactide. The degradation process of the materials was examined during immersion in distilled water at 80 °C for 60 days using differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Macroscopic changes were monitored and mechanical properties tested prior to degradation to evaluate the ability of the modified clay filler to reinforce the polymer and enhance elastic modulus, mechanical strength and Brinell hardness. The influence of the modified smectite filler on the thermal, mechanical and structural properties of the nanocomposites during degradation and its dependence on filler content were discussed and confirmed in the study. It was found that the addition of 3 mass% of the clay filler provides an increase of nearly 20 % in tensile strength, with improved stiffness. It was also found that the addition of organically modified clay to the polymer matrix significantly changes the hydrolytic degradation mechanisms of the polylactide, the crystallinity of the polymer and its degradation rate, depending on the amount of the filler.

In this comparative study, the influence of the organophilisation process on the properties of resulting organobentonite fillers and their capability to improve the mechanical properties of clay/polymer nanocomposites were investigated. The organobentonites were obtained by activation with the use of two organic quaternary ammonium salts (QAS) with alkyl chains of significantly different lengths. The organophilisation resulted in an increase in the interlayer space of clays, which was confirmed by XRD analysis. The obtained organofillers were used to produce nanoclay/epoxy resin composites and the effects of alkyl chain length on the resulting properties of composites were compared based on the examination of mechanical behaviour and morphology, and a composite filled with the non organophilised bentonite was used as a reference material. It was demonstrated that the organophilisation process using distearyldimethyl ammonium chloride salt with a longer alkyl chain (C18-C20) created a more superior conditions for the compatibility of nanofiller with a polymer matrix, resulting in a 25 % increase in the bending strength of the epoxy composite material filled with 3 %wt of the organophilised bentonite, comparing to neat epoxy.

In the context of product development, the term rapid prototyping (RP) is widely used to describe technologies which create physical prototypes directly from digital data. Recently, this technology has become one of the fastest-growing methods of manufacturing parts. The paper provides brief notes on the creation of composites using RP methods, such as stereolithography, selective laser sintering or melting, laminated object modelling, fused deposition modelling or three-dimensional printing. The emphasis of this work is on the methodology of composite fabrication and the variety of materials used in these technologies.

The article presents results of research on microstructural and mechanical properties of floor tiles clinker manufactured on the basis of Wierzbka I raw material, which is part of the deposit Wierzbka, near Suchedniów. Wierzbka I clay was added in various volume fractions to the standard tile compositions used in industrial practice. The samples were pressed in a range of from 21 MPa to 42 MPa and fired in the laboratory furnace at 1130°C to 1190°C. Selected compositions were pressed at 28 MPa and fired in a standard industrial environment. The process of firing was conducted in an industrial kiln at temperature of 1160°C for 38 minutes, with holding for 4 minutes at maximum operating temperature. The samples, which were prepared in the laboratory and industrial conditions were evaluated for the effect of addition of the Wierzbka I clay on their microstructural and mechanical properties based on the measurement results of linear shrinkage, bulk density, open porosity, water absorption and flexural strength (Ϭ) of the tiles. Microstructural changes were observed with a scanning electron microscope (SEM). The results revealed that the tested tiles were characterized by a high degree of sintering, an apparent density of 2.5 g/cm3, an open porosity and water absorption below 0.5%. The measurement results of mechanical bending strength showed that the tested samples had a high strength of 50 MPa.

The paper presents results of research on the assessment of the suitability of the Wierzbka I Triassic clay raw materials, which are part of the Wierzbka deposit near Suchedniów, for the production of clinker tiles obtained by pressing. Red colour clays are often used in the production technology of clinker tiles. The high content of Fe2O3 in the composition of red clays promotes the sintering process and affects the colour of the resulting material, a typical characteristic of clinker materials. The raw materials used in this technology should have good sinterability, which guarantees a material with low water absorption, high chemical resistance and mechanical strength. Samples of the raw materials were taken from three different depths of the deposit, and subjected to analysis as follows: chemical composition, phase composition (XRD, thermal analysis DSC/TG), sintering shrinkage, sintering curve and the characteristic temperatures. The analysis of the microstructure was determined using scanning electron microscopy (SEM). The X-ray and thermal analysis of the studied clays revealed the presence of clay minerals such as: illite, kaolinite, illite/smectite, but also quartz and ferruginous minerals. There was no presence of calcium carbonate in the tested samples of the raw clay, which particularly distinguishes these materials as being suitable for use in the fast firing technology of clinker tiles. Samples of the raw materials were pressed under a pressure ranging from 21 to 42 MPa and then fired at temperatures in the range 1130 to 1220°C. The obtained sintered bodies were characterized by a high degree of sintering, an apparent density of 2.31g/cm3, an open porosity of less than 2.5% and water absorption below 1.0%. The results of this study indicate a high technological value of raw materials from the Wierzbka I deposit.

The effect of the BaO addition on the microstructure and structure of the glasses from the K2O–MgO–CaO–Al2O3–SiO2-(BaO) system was investigated in this study. The results were obtained by testing the crystallization capability of the glasses during the fast-firing cycle. Thermal analysis proved a high tendency to crystallize the tested glasses/frits. X-ray analysis showed the presence of diopside and anorthite as the main crystalline phases in all glazes obtained from the tested glasses. Microscopic observations showed that barium oxide introduced in the range of 0.4–2.1 mol% into the examined system strongly influences the number and size of crystalline phases. The introduction of 2.1 mol% BaO into the composition also resulted in crystallization of celsian. The thermal characteristic of the glasses was carried out using differential scanning calorimetry (DSC) and the crystalline phases were determined by X-ray diffractometry. The glaze microstructure was investigated by scanning (SEM) and transmission electron (TEM)microscopy. Additional information on the structure of frits was derived from mid-infrared (MIR) and Raman spectroscopy.

The extracellular matrix (ECM) can be a convenient scaffold used in tissue engineering, regenerative medicine and pharmacy. The synthetic cell matrix should imitate the natural extracellular matrix in both composition and architecture. The study examined fibrous chitosan modified with fragments of human collagen I (10–15 amino acids) mimicking the internal sphere of native protein. The surface of chitosan fibers was modified by physical and chemical methods to obtain polysaccharide-peptide conjugates, which may be considered analogous to the complex of glycosaminoglycans (GAG) and peptides present in the cell matrix. The surface of fibrous chitosan was enriched with fragments of human collagen I, using physicochemical properties (water absorption during electrospraying) and chemical compatibility (activity of amide and peptide groups) during synthesis. The method of modification had an effect on changing the diameter of the fibers and their topography, as assessed by means of a scanning electron microscopy (SEM). The presence of peptides on the surface of the fibers was confirmed by spectroscopic studies (FTIR-ATR and FT Raman). It has been shown that the chemical modification provided a homogeneous distribution of the peptide on the fiber, without changing its morphology as opposed to the physical modification of the fiber, which is visible on the surface in the form of peptide aggregates. The biocompatibility of the materials thus obtained was confirmed during biological studies using MG-63 osteoblast-like cells. Correct morphology observed after 3 days of culture (live-dead test) confirmed the suitability of the substrates for biomedical applications.

Comparative studies were performed on variations in the ABO3 perovskite structure, chemical stability in a CO2-H2 gas atmosphere, and electrical conductivity measurements in air, hydrogen, and humidity-involving gas atmospheres of monophase orthorhombic Ba1−xSrxCe0.9Y0.1O3−δ samples, where 0 < x < 0.1. The substitution of strontium with barium resulting in Ba1−xSrxCe0.9Y0.1O3−δ led to an increase in the specific free volume and global instability index when compared to BaCe0.9Y0.1O3−δ. Reductions in the tolerance factor and cell volume were found with increases in the value of x in Ba1−xSrxCe0.9Y0.1O3−δ. Based on the thermogravimetric studies performed for Ba1−xSrxCe0.9Y0.1O3−δ, where 0 < x < 0.1, it was found that modified samples of this type exhibited superior chemical resistance in a CO2 gas atmosphere when compared to BaCe0.9Y0.1O3−δ. The application of broadband impedance spectroscopy enabled the determination of the bulk and grain boundary conductivity of Ba1−xSrxCe0.9Y0.1O3−δ samples within the temperature range 25–730 °C. It was found that Ba0.98Sr0.02Ce0.9Y0.1O3−δ exhibited a slightly higher grain interior and grain boundary conductivity when compared to BaCe0.9Y0.1O3−δ. The Ba0.95Sr0.05Ce0.9Y0.1O3−δ sample also exhibited improved electrical conductivity in hydrogen gas atmospheres or atmospheres involving humidity. The greater chemical resistance of Ba1−xSrxCe0.9Y0.1O3−δ, where x = 0.02 or 0.05, in a CO2 gas atmosphere is desirable for application in proton ceramic fuel cells supplied by rich hydrogen processing gases.

The aim of this study was to evaluate the effect of the not activated (unmodified) montmorillonite (MMT) filler on the antibacterial properties of polymer nanocomposites with a biodegradable polylactide (PLA) matrix. The subject of research was selected to verify the reports on the lack of antibacterial properties of unmodified montmorillonite in nanocomposites and to investigate the potential conditions of their manufacturing which are decisive for the resulting properties. Evaluation of antibacterial and mechanical properties of both the starting materials and the obtained nanocomposites filled with layered silicates as well as the wettability of the materials, measured by a sitting drop method was made on samples in the form of a film. The results show that the surface wettability of the polymer nanocomposites did not exhibit significant change compared to the film of neat PLA. However, a significant improvement in the mechanical and antimicrobial properties of the nanocomposite films obtained in a specific solvent casting process of the nanocomposite preceded by exfoliation of the film in an ultrasonic homogenizer was demonstrated. The antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Enterococcus faecalis was also observed, and, moreover, the montmorillonite-containing films revealed a zone of inhibition of bacterial growth when tested against the lactosepositive bacteria of the Enterobacteriaceae family, which are present in the waste water. The advantageous properties of the obtained PLA/MMT nanocomposites suggest that the unmodified montmorillonite may be potentially used as filler for polymer films in the packaging industry.

This paper focusses on the intercalation of clay mineral with gentamicin (an aminoglycoside antibiotic). The smectite clay–gentamicin hybrids were prepared by a solution intercalation at 60∘C and the process was carried out on unmodified smectite clay and on smectite after Na+ ionic activation. The resulting structural/microstructural properties and the potential for introducing gentamicin between smectite clay layers were investigated by means of X-ray diffraction, Fourier transform infrared spectroscopic techniques and transmission electron microscopy and scanning electron microscopy with energy-dispersive spectroscopy X-ray analysis. The results confirm the successful intercalation of gentamicin into the interlayer space of smectite clay, demonstrating that the material thus obtained could potentially be used as a drug carrier.

Although the degradation of polylactide has been relatively well understood, there is still a lack of reliable data on the behavior of its composites at specific temperatures. This paper studies the hydrolytic degradability of polylactide/not activated smectite clay nanocomposites in the 6 weeks accelerated degradation at 80 °C which has not been widely documented so far. The composites with 3 wt%, 5 wt% and 10 wt% of smectite filler content obtained by injection molding were investigated and compared to the neat polylactide matrix material. The results of degradation at 80 °C were referred to the hydrolytic degradation at 25 °C and 37 °C. Macroscopic changes in the nanocomposites, their molecular weight and pH of medium was monitored during the degradation time. The influence of clay addition on the crystallization, glass transition and the melting temperature was also studied by differential scanning calorimetry (DSC). The DSC results show that the presence of smectite clay results in a shift of the onset peak for the melting temperatures towards higher values while for the glass transition towards the lower ones. A significant difference in degradation rate between the polylactide matrix and the polylactide/clay nanocomposites was also noted. The shortened degradation time of the nanocomposites increases their potential for use in biomedical applications, but also in disposable thermoplastic products which are increasingly used.

This paper presents the results of the phase composition study of model systems containing all the main components of the mixtures, used in the laboratory tests of concretes, namely, Al 2 O 3 , CaO and P 2 O 5 . Samples were analysed using X-ray analysis and scanning electron microscopy with EDS analysis in microregions. Four mixtures were tested: one corundum-rich with a small amount of aluminium phosphate and calcium oxide, and three with a high content of aluminium phosphate with the addition of calcium oxide and calcium aluminate. Mixtures to which phosphoric acid was added instead of aluminium phosphate were also studied. It was found that in the model mixtures corresponding to the composition of corundum refractory concretes with small amount of phosphates, two phases are formed, during operation at a temperature of 1400 °C, namely Ca 3 (PO 4 ) 2 and Ca(Al 12 O 19 ). The addition of phosphoric acid resulted in the concrete having the same phase composition as it would had aluminium phosphate and alumina cement been added instead.

The aim of this study was evaluation of distribution microelements in human articular cartilage and to determine factors influencing it. The following elements were taken under consideration: Mg, Ca, Zn, Fe, Pb. Their concentration was assessed in the articular cartilage harvested from the loaded an unloaded area of human femoral heads. Initial results indicate that mechanical loadings are one of the important factors influencing distribution of microelements in human articular cartilage.

The aim of the work was the deposition of polymer fibres of submicrometric and nanometric diameter. A layer of the fibres was produced from biocompatible polymer, i.e. poli (ε) caprolactane (PCL). The polymer was dissolved in a mixture of DMF:DCM solvents. In order to enhance the hydrophobic effect, silica particles (5–10 nm) were introduced into the polymer solution. PCL fibres were produced using electric field of 25 kV. Wettability of the produced layer was determined using the method of sitting drop (DSA T500). Its microstructure was observed using scanning an electron microscope (Nova NanoSEM) and an atomic force microscope (MULTIMODE 8 AFM, Bruker). It was revealed that only coatings made of the pure polymer fibres showed superhydrophobicity (PCL fibres, wetting angle of 151o), while the nanocomposite fibres made of PCL and 3 wt.% SiO2 formed a layer with a wetting angle of 113o, which was more hydrophobic than a conventional polymer layer made by casting (wetting angle of PCL foil is 90o).

The effect of the addition of polypropylene fibres to the corundum concretes containing both high-aluminate cement and aluminium phosphate on the compactness, gas-permeability and pore distribution has been investigated. The mercury porosimetry test results revealed that concretes with the addition of polypropylene fibres, as compared with concretes containing no fibres, exhibit microstructure with an increased quantity of pores of a diameter of about 17 μm, which corresponds in approximation to the fibre diameter and is comparable to AlPO4-containing concretes and to concretes containing aluminate cement only. Specimens of the AlPO4-containing concrete with no fibre addition have lower gas-permeability at temperatures of 110 and 300 °C, as compared to specimens of concrete with aluminate cement only. For both concretes with the polypropylene fibre addition, a similar gas-permeability and its increase with the increase in heating temperature were reported. This is caused most probably by burning out of the fibres creating a micro-channels system in the concrete, which facilitates the gas flow. For these concretes, an increase in the volume of pores is also observed after heating at a temperature of both 110 °C, and 1500 °C.

Calcium zirconate powders doped with a small amount of CaO were synthesised using the Pechini method. X-ray analysis revealed that solid solution was formed in the concentration up to 51.5% mol CaO. For synthesis of stoichiometric CaZrO3, the highest temperature was required (1150°C), but introduction of excess CaO from 50.5 to 51.5% mol enabled us to lower the synthesis temperature to 800°C. The sintering behaviour of such samples under non-isothermal conditions was studied by dilatometric methods. Deviations were found in stoichiometry; by increasing the CaO concentration in CaZrO3 sinterability improved in comparison to CaZrO3 with stoichiometric composition. The presence of CaO as second phase caused deterioration of the sinterability of the CaZrO3-based samples. Pellets sintered at 1500°C for 2 h reached 96–98% of theoretical density. SEM and TEM observations were used to characterise the microstructure of the prepared samples. The electrical properties of CaZrO3-based samples were investigated by the AC-impedance spectroscopy method. It was found that introduction of excess CaO into the CaZrO3 structure caused an increase in ionic conductivity up to the solubility limit. The possibility of using CaZrO3-based samples for constructing prototype electrochemical oxygen probes to determine activity of oxygen dissolved in molten copper is also demonstrated.

The Pechinni method (A) as well as hydrothermal treatment (B) of co-precipitated CeO2-based gels with NaOH solution were used to synthesise pure CeO2, and CeO2-based solid solutions with formula Ce1−xMxO2, Ce1−x(M0.5Ca0.5)xO2 M = Gd, Sm for 0.15

The surface charge at the calcium phosphate/electrolyte interface is created as a result of the various reactions of surface groups and unequal adsorption of ions of an opposite charge from the solution. Photoacoustic spectroscopy (FT-IR/PAS) has been used for identification of different groups of hydroxy- apatite samples. A complementary study of electrical double layer properties was carried out using potentiometric titration and electrophoretic measurements.

Hydroxyapatite is a well-known and valuable implant material with bioactive properties. Full utilisation of the unique properties of hydroxyapatite ceramics is, however, possible only after its proper reinforcement, i.e., by preparation of composites. In the present work zirconia reinforced hydroxyapatite composites were obtained by hot pressing method. The reinforcing phase in the form of ZrO 2 particles was selected due to the satisfactory biocompatibility of ZrO 2 and also because of its exceptional mechanical properties. Our investigations were aimed at assessing the influence of varying ZrO 2 on the phase composition and mechanical properties of HAp–ZrO 2 composites. In order to produce dense sinters, we used three types of initial zirconia powders which differed in morphology and contents of the tetragonal and monoclinic phases. We studied the influence of these oxides on thermal stability of hydroxyapatite matrix as well as on the phase composition and mechanical properties of the composite materials produced.

Performance of hydroxyapatite material in a living body depends on a number of factors. Stability of hydroxyapatite structure, which is influenced by both, preparation conditions of the starting precursor powders and fabrication method of the implant materials, is an important one. Inappropriate preparation conditions of synthesis, calcination of powder and sintering of formed samples result in dehydroxylation and even in decomposition of HAp which lead to the change in the physicochemical properties of implants. In the work samples of hydroxyapatite ceramics have been obtained by two methods, i.e. by hot pressing and by pressureless sintering in the temperature range of 1150–1300 °C. The materials prepared have been studied using FTIR and XRD in order to identify the dehydroxylation processes and the possible hydroxyapatite decomposition during thermal treatment. The usefulness of both methods in identification of thermal stability of hydroxyapatite was confirmed.

Applicational properties of HAp–ZrO2 composite coatings prepared on a titanium alloy substrate using plasma spraying method and analogous HAp coatings are compared. Results of the studies indicate that there is a strong dependence of the phase composition, thickness, porosity and adhesion to the substrate of the obtained coatings on the characteristics of the starting powders used for their preparation.

During the production of biomedical hydroxyapatite–zirconia (HAp–ZrO 2 ) composites new phases which determine the biocompatibility of implant materials may occur in the system. These phenomena may be associated both with the phase decomposition of hydroxyapatite itself and the interactions between the matrix material and particles of reinforcing zirconia phase. The work deals with the investigations of phase stability of HAp–ZrO 2 composites at high temperature. The composites studied have been in the form of dense sinters obtained by the hot pressing process.

Composite samples were obtained from hydroxyapatite powder and carbon fibres by hot pressing at 1100°C and 25 MPa for 15 min in argon atmosphere. Two types of cut carbon fibres produced in a carbonisation process of polyacrylonitrile (PAN) precursor were used both in non-coated or coated form. The coatings of calcium phosphate were applied by sol–gel technique. The highly sintered composite with the best strength properties was obtained from coated carbon fibres with basic character of the surface. The existence of hydroxyl groups on fibre surface makes possible formation of bonds with the calcium phosphate layer formed as a result of polycondensation following the sol–gel procedure.

In recent years researchers all over the world have been interested in obtaining the evaluation and medical applications of the composites based on calcium phosphates, mainly hydroxyapatite and TCP. Hydroxyapatite (HAp)-Ca10(PO4)6(OH)2 is a material of high biocompatibility and additionally it is also one of the few bioactive materials able to create direct, and thus permanent, bonding with the bone tissue [1–3]. Full use of the unique properties of the dense hydroxyapatite ceramics is potentially possible only if their mechanical strength and fracture toughness are improved. These effects can be achieved in composite materials with HAp matrix. Among various reinforcing phases applied in the form of particles, platelets, fibers and nanoparticles, zirconia (ZrO2) seems to be the most interesting one, due to its excellent mechanical properties [4]. Toughening mechanism utilizing the tetragonal—monoclinic transformation of ZrO2 as well as the microcracking toughening mechanism resulting from the difference in thermal expansion coefficients of hydroxyapatite and zirconia are expected to occur in HAp-ZrO2 composites [5]. The biological inertness and good biocompatibility of ZrO2 sinters were confirmed by their medical applications [6]. However, in the case of composites containing substrates of excellent biocompatibility, it cannot be assumed that the final material will exhibit the same high level of biocompatibility. Numerous phenomena which occur during the materials processing may affect the phase composition, microstructure, and other properties responsible for the biological reactions. Therefore it is important to perform tests which evaluate the behavior of a composite material in conditions simulating an environment in a living organism. The objective of our study was manufacturing and comparative in vitro evaluation of the HAp-ZrO2 composite and monophase HAp sinters obtained by hot pressing method. The study was performed on dense composite sinters (HAp80 wt%-ZrO220 wt%) and pure HAp used as a reference material. Non-stabilized zirconia powder was produced by precipitation of hydrated ZrO2 from ZrOCl2·8H2O aqueous solution [7]. The HApZrO2 composite powder was synthesized by precipitation of hydroxyapatite in the presence of ZrO2 (wet process). The weighed amount of ZrO2 powder was added to the intensively stirred aqueous suspension of Ca(OH)2. Then the solution of H3PO4 was added slowly to the reaction medium. The precipitate produced was rinsed with distilled water, dried, calcined at 800 ◦C for three hours, and then ground. The composite powder obtained was an initial material for the production of dense HAp-ZrO2 sinters. Hydroxyapatite for dense monophase HAp material was synthesized by the wet method using CaO and H3PO4 as reagents [8]. The precipitate was treated as described above. The samples of monophase HAp ceramics and HApZrO2 composite were hot pressed in the temperature range of 1150 ÷ 1300 ◦C (Thermal Technology Inc. kiln). The pressing was performed in graphite molds under argon atmosphere at a pressure of 25 MPa with a 0.5 hr soaking time, at the highest temperature. The cytotoxicity analyses performed in this study constitute one of the stages of biological analyzes used for evaluation of broadly understood material biocompatibility. Although in vitro systems may not reflect normal in vivo conditions accurately, a cell-culture system is useful to observe phenomena at the cellular level. Such systems have been used to evaluate biocompatibility of implant materials and to study the interactions occurring at the cell-material interface [9]. The whole range of biocompatibility analyzes depends on the duration and kind of contact between an implant material and an organism, and is determined according to the PN-EN ISO 10993-1:1997 standard. The cytotoxicity analyzes are fast, standardised tests which can determine if a given material designed for medical applications contains significant amounts of biologically harmful substances. High sensitivity of these tests result from the isolation of cell cultures and thus lack of defence mechanisms, which accompany the cells within the body. The cytotoxicity tests were performed on the samples according to the standard PN-EN ISO 10993-5 “Biological evaluation of medical products. Cytotoxicity investigations: in vitro methods”. A method of direct contact with a layer of mouse fibroblasts 3T3/Balb evenly

In this paper a brief characterization of fuel cell technology and its possible application in sustainable energy development was described. Special attention was paid to direct carbon fuel cell technology. The direct carbon fuel cell is an electrochemical device which directly converts the chemical energy of carbonaceous based fuel into electricity without ‘flame burning’. The electrical efficiency of a DCFC is indeed very high (in practice exceeding 80%), and the product of conversion consists of almost pure CO2 , eliminating the most expensive step of sequestration: the separation of carbon from flue gases. In this paper the process of electrochemical oxidation of carbon particles on the surface of oxide electrolytes at 8% mol Y2 O3 in ZrO2 (8YSZ) as well as cermet anode Ni-8YSZ was analysed. The graphite, carbon black powders were considered as reference solid fuels for coal samples. It was found that the main factors contributing to the electrochemical reactivity of carbon particles is not only the high carbon content in samples but also structural disorder. It was found that structurally disordered carbon-based materials are the most promising solid fuels for direct carbon solid oxide fuel cells. Special impact was placed on the consideration of coal as possible solid fuels for DC-SOFC. Statistical and economic analyses show that in the coming decades, in developing countries such as China, India, and some EU countries, coal-fuelled power plants will maintain their strong position in the power sector due to their reliability and low costs as well as the large reserves of coal and lignite in the world. Coal is mined in politically stable areas, which guarantees its easy and safe purchase and transport. The impact of the physiochemical properties of raw and purified coal on the performance of the DC-SOFC was studied. An analysis of the stability of electrical parameters was performed for a DC-SOFC operating under a load over an extended period of time. The tests indicated that DC-SOFCs fed with de-ashed coal were characterized by stable operation, with a power density greater than 100 mW/cm2 from a single cell.